Don't understand why holes needs to be connected to edge
There's evidently some critical conditions that an ngon can't exist under.
If you take an example with only one hole, you'll see you are completely unable to dissolve these edges.

When I cut two holes I got a different result from you, and I was unable to dissolve any edges.

Until I added a new edge in the center like you have, and then you are able to dissolve a couple.  I get one less edge than yours.

But each of these remains a shape with a definite inside and outside, and that allows a face to be constructed from it.
I'm unaware of the exact limits placed on ngons, but my best guess is that these are very close to the simplest shapes possible that still allow you to draw triangles without drawing through an area where the mesh shouldn't have a face.

(I kind of misplaced the X here, maybe)
You can use a Triangulate modifier in Wireframe view to visualize.